The overall objective of this proposal is to maintain a Pneumococcal Polysaccharide Serological Reference Laboratory for the purpose of providing a standardized reproducible quantitative system for analyses of antibody responses to pneumococcal polysaccharide vaccines as well as determination of antibody levels during the course of natural disease, surgical intervention (such as splenectomy), drug or radiation therapy, HIV infections and other assaults on the immune system. The Pneumococcal Polysaccharide Reference Laboratory will be capable of performing radioimmunoassay analyses on sera derived from NIAID approved projects in excess of 75,000 assays per year under conditions that the results will be comparable from study to study, from year to year. The Pneumococcal Polysaccharide Reference Laboratory will have available 14C internally labelled biosynthetic pneumococcal capsular polysaccharide of each of the 23 serotypes present in the current pneumococcal vaccine. These reagents will be available to investigators at the request of the project officer. The Pneumococcal Polysaccharide Reference Laboratory will have available purified pneumococcal polysaccharides, unlabelled, available for other investigators wishing to perform ELISA assays and for use in inhibition type measurements. The Pneumococcal Polysaccharide Reference Laboratory will also have available lyophilized preparations of each of the 82 pneumococcal serotypes which can be used to prepare radioactive antigens, unlabeled capsular polysaccharides, vaccines for rabbit immunization to be used for typing or subtyping and for other studies such as opsonization, mouse protection or purification of specific antibody. The Pneumococcal Polysaccharide Reference Laboratory will have available a complete set of 48 typing sera, obtained from Staten Serum Institute, Copenhagen, Denmark, for typing organisms isolated from patients, or to check the authenticity of organisms used in collaborative studies such as opsonization, phagocytosis or mouse protection tests.